don't wipe out the failures. gosh there were a ton of these

This commit was sponsored by Steven S., and my other patrons.  If you
want to join them, you can support my work at
https://glyph.im/patrons/.

src/dbxs/_testing.py

@@ -146,24 +146,19 @@ def schedule(
 @dataclass
 class DeferredCompletionTester:
     failer: Callable[[str], None]
-    deferred: Deferred[object]
+    succeeded: list[object]
+    failed: list[Failure]
 
     def assertNoResult(self) -> None:
-        succeeded: list[object] = []
-        failed: list[Failure] = []
-        self.deferred.addCallbacks(succeeded.append, failed.append)
-        if failed:
-            failed[0].raiseException()
-        if succeeded:
-            self.failer(f"unexpected result {succeeded[0]}")
+        if self.failed:
+            self.failed[0].raiseException()
+        if self.succeeded:
+            self.failer(f"unexpected result {self.succeeded[0]}")
 
     def assertSuccessResult(self) -> None:
-        succeeded: list[object] = []
-        failed: list[Failure] = []
-        self.deferred.addCallbacks(succeeded.append, failed.append)
-        if failed:
-            failed[0].raiseException()
-        if not succeeded:
+        if self.failed:
+            self.failed[0].raiseException()
+        if not self.succeeded:
             self.failer("no result")
 
 
@@ -173,10 +168,11 @@ def schedule(
         failer: Callable[[str], None],
         coroutine: Coroutine[Any, Any, Any],
     ) -> CompletionTester:
-        return DeferredCompletionTester(
-            failer,
-            Deferred.fromCoroutine(coroutine),
-        )
+        succeeded: list[object] = []
+        failed: list[Failure] = []
+        deferred = Deferred.fromCoroutine(coroutine)
+        deferred.addCallbacks(succeeded.append, failed.append)
+        return DeferredCompletionTester(failer, succeeded, failed)
 
 
 def immediateTest(

src/dbxs/test/test_testing.py

@@ -38,7 +38,7 @@ async def method(self: TestFailing, pool: MemoryPool) -> None:
 
     def test_failsBeforeBlocking(self) -> None:
         """
-        If an @immediateTest raises an exception, taht exception is re-raised.
+        If an @immediateTest raises an exception, that exception is re-raised.
         """
 
         @immediateTest()
@@ -47,3 +47,17 @@ async def method(self: TestFailing, pool: MemoryPool) -> None:
 
         with self.assertRaises(ZeroDivisionError):
             method(self)
+
+    def test_failsAfterBlocking(self) -> None:
+        """
+        If an @immediateTest raises an exception after blocking, that exception
+        is re-raised as well.
+        """
+
+        @immediateTest()
+        async def method(self: TestFailing, pool: MemoryPool) -> None:
+            await pool.connectable.connect()
+            1 / 0
+
+        with self.assertRaises(ZeroDivisionError):
+            method(self)